1 /* $OpenBSD: sshd.c,v 1.366 2009/01/22 10:02:34 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * This program is the ssh daemon. It listens for connections from clients, 7 * and performs authentication, executes use commands or shell, and forwards 8 * information to/from the application to the user client over an encrypted 9 * connection. This can also handle forwarding of X11, TCP/IP, and 10 * authentication agent connections. 11 * 12 * As far as I am concerned, the code I have written for this software 13 * can be used freely for any purpose. Any derived versions of this 14 * software must be clearly marked as such, and if the derived work is 15 * incompatible with the protocol description in the RFC file, it must be 16 * called by a name other than "ssh" or "Secure Shell". 17 * 18 * SSH2 implementation: 19 * Privilege Separation: 20 * 21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 22 * Copyright (c) 2002 Niels Provos. All rights reserved. 23 * 24 * Redistribution and use in source and binary forms, with or without 25 * modification, are permitted provided that the following conditions 26 * are met: 27 * 1. Redistributions of source code must retain the above copyright 28 * notice, this list of conditions and the following disclaimer. 29 * 2. Redistributions in binary form must reproduce the above copyright 30 * notice, this list of conditions and the following disclaimer in the 31 * documentation and/or other materials provided with the distribution. 32 * 33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 43 */ 44 45 #include "includes.h" 46 47 #include <sys/types.h> 48 #include <sys/ioctl.h> 49 #include <sys/socket.h> 50 #ifdef HAVE_SYS_STAT_H 51 # include <sys/stat.h> 52 #endif 53 #ifdef HAVE_SYS_TIME_H 54 # include <sys/time.h> 55 #endif 56 #include "openbsd-compat/sys-tree.h" 57 #include "openbsd-compat/sys-queue.h" 58 #include <sys/wait.h> 59 60 #include <errno.h> 61 #include <fcntl.h> 62 #include <netdb.h> 63 #ifdef HAVE_PATHS_H 64 #include <paths.h> 65 #endif 66 #include <grp.h> 67 #include <pwd.h> 68 #include <signal.h> 69 #include <stdarg.h> 70 #include <stdio.h> 71 #include <stdlib.h> 72 #include <string.h> 73 #include <unistd.h> 74 75 #include <openssl/dh.h> 76 #include <openssl/bn.h> 77 #include <openssl/md5.h> 78 #include <openssl/rand.h> 79 #include "openbsd-compat/openssl-compat.h" 80 81 #ifdef HAVE_SECUREWARE 82 #include <sys/security.h> 83 #include <prot.h> 84 #endif 85 86 #include <resolv.h> 87 #include "xmalloc.h" 88 #include "ssh.h" 89 #include "ssh1.h" 90 #include "ssh2.h" 91 #include "rsa.h" 92 #include "sshpty.h" 93 #include "packet.h" 94 #include "log.h" 95 #include "buffer.h" 96 #include "servconf.h" 97 #include "uidswap.h" 98 #include "compat.h" 99 #include "cipher.h" 100 #include "key.h" 101 #include "kex.h" 102 #include "dh.h" 103 #include "myproposal.h" 104 #include "authfile.h" 105 #include "pathnames.h" 106 #include "atomicio.h" 107 #include "canohost.h" 108 #include "hostfile.h" 109 #include "auth.h" 110 #include "misc.h" 111 #include "msg.h" 112 #include "dispatch.h" 113 #include "channels.h" 114 #include "session.h" 115 #include "monitor_mm.h" 116 #include "monitor.h" 117 #ifdef GSSAPI 118 #include "ssh-gss.h" 119 #endif 120 #include "monitor_wrap.h" 121 #include "version.h" 122 123 #ifdef LIBWRAP 124 #include <tcpd.h> 125 #include <syslog.h> 126 int allow_severity; 127 int deny_severity; 128 #endif /* LIBWRAP */ 129 130 #ifndef O_NOCTTY 131 #define O_NOCTTY 0 132 #endif 133 134 /* Re-exec fds */ 135 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 136 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 137 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 138 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 139 140 extern char *__progname; 141 142 /* Server configuration options. */ 143 ServerOptions options; 144 145 /* Name of the server configuration file. */ 146 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 147 148 /* 149 * Debug mode flag. This can be set on the command line. If debug 150 * mode is enabled, extra debugging output will be sent to the system 151 * log, the daemon will not go to background, and will exit after processing 152 * the first connection. 153 */ 154 int debug_flag = 0; 155 156 /* Flag indicating that the daemon should only test the configuration and keys. */ 157 int test_flag = 0; 158 159 /* Flag indicating that the daemon is being started from inetd. */ 160 int inetd_flag = 0; 161 162 /* Flag indicating that sshd should not detach and become a daemon. */ 163 int no_daemon_flag = 0; 164 165 /* debug goes to stderr unless inetd_flag is set */ 166 int log_stderr = 0; 167 168 /* Saved arguments to main(). */ 169 char **saved_argv; 170 int saved_argc; 171 172 /* re-exec */ 173 int rexeced_flag = 0; 174 int rexec_flag = 1; 175 int rexec_argc = 0; 176 char **rexec_argv; 177 178 /* 179 * The sockets that the server is listening; this is used in the SIGHUP 180 * signal handler. 181 */ 182 #define MAX_LISTEN_SOCKS 16 183 int listen_socks[MAX_LISTEN_SOCKS]; 184 int num_listen_socks = 0; 185 186 /* 187 * the client's version string, passed by sshd2 in compat mode. if != NULL, 188 * sshd will skip the version-number exchange 189 */ 190 char *client_version_string = NULL; 191 char *server_version_string = NULL; 192 193 /* for rekeying XXX fixme */ 194 Kex *xxx_kex; 195 196 /* 197 * Any really sensitive data in the application is contained in this 198 * structure. The idea is that this structure could be locked into memory so 199 * that the pages do not get written into swap. However, there are some 200 * problems. The private key contains BIGNUMs, and we do not (in principle) 201 * have access to the internals of them, and locking just the structure is 202 * not very useful. Currently, memory locking is not implemented. 203 */ 204 struct { 205 Key *server_key; /* ephemeral server key */ 206 Key *ssh1_host_key; /* ssh1 host key */ 207 Key **host_keys; /* all private host keys */ 208 int have_ssh1_key; 209 int have_ssh2_key; 210 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 211 } sensitive_data; 212 213 /* 214 * Flag indicating whether the RSA server key needs to be regenerated. 215 * Is set in the SIGALRM handler and cleared when the key is regenerated. 216 */ 217 static volatile sig_atomic_t key_do_regen = 0; 218 219 /* This is set to true when a signal is received. */ 220 static volatile sig_atomic_t received_sighup = 0; 221 static volatile sig_atomic_t received_sigterm = 0; 222 223 /* session identifier, used by RSA-auth */ 224 u_char session_id[16]; 225 226 /* same for ssh2 */ 227 u_char *session_id2 = NULL; 228 u_int session_id2_len = 0; 229 230 /* record remote hostname or ip */ 231 u_int utmp_len = MAXHOSTNAMELEN; 232 233 /* options.max_startup sized array of fd ints */ 234 int *startup_pipes = NULL; 235 int startup_pipe; /* in child */ 236 237 /* variables used for privilege separation */ 238 int use_privsep = -1; 239 struct monitor *pmonitor = NULL; 240 241 /* global authentication context */ 242 Authctxt *the_authctxt = NULL; 243 244 /* sshd_config buffer */ 245 Buffer cfg; 246 247 /* message to be displayed after login */ 248 Buffer loginmsg; 249 250 /* Unprivileged user */ 251 struct passwd *privsep_pw = NULL; 252 253 /* Prototypes for various functions defined later in this file. */ 254 void destroy_sensitive_data(void); 255 void demote_sensitive_data(void); 256 257 static void do_ssh1_kex(void); 258 static void do_ssh2_kex(void); 259 260 /* 261 * Close all listening sockets 262 */ 263 static void 264 close_listen_socks(void) 265 { 266 int i; 267 268 for (i = 0; i < num_listen_socks; i++) 269 close(listen_socks[i]); 270 num_listen_socks = -1; 271 } 272 273 static void 274 close_startup_pipes(void) 275 { 276 int i; 277 278 if (startup_pipes) 279 for (i = 0; i < options.max_startups; i++) 280 if (startup_pipes[i] != -1) 281 close(startup_pipes[i]); 282 } 283 284 /* 285 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 286 * the effect is to reread the configuration file (and to regenerate 287 * the server key). 288 */ 289 290 /*ARGSUSED*/ 291 static void 292 sighup_handler(int sig) 293 { 294 int save_errno = errno; 295 296 received_sighup = 1; 297 signal(SIGHUP, sighup_handler); 298 errno = save_errno; 299 } 300 301 /* 302 * Called from the main program after receiving SIGHUP. 303 * Restarts the server. 304 */ 305 static void 306 sighup_restart(void) 307 { 308 logit("Received SIGHUP; restarting."); 309 close_listen_socks(); 310 close_startup_pipes(); 311 alarm(0); /* alarm timer persists across exec */ 312 execv(saved_argv[0], saved_argv); 313 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 314 strerror(errno)); 315 exit(1); 316 } 317 318 /* 319 * Generic signal handler for terminating signals in the master daemon. 320 */ 321 /*ARGSUSED*/ 322 static void 323 sigterm_handler(int sig) 324 { 325 received_sigterm = sig; 326 } 327 328 /* 329 * SIGCHLD handler. This is called whenever a child dies. This will then 330 * reap any zombies left by exited children. 331 */ 332 /*ARGSUSED*/ 333 static void 334 main_sigchld_handler(int sig) 335 { 336 int save_errno = errno; 337 pid_t pid; 338 int status; 339 340 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 341 (pid < 0 && errno == EINTR)) 342 ; 343 344 signal(SIGCHLD, main_sigchld_handler); 345 errno = save_errno; 346 } 347 348 /* 349 * Signal handler for the alarm after the login grace period has expired. 350 */ 351 /*ARGSUSED*/ 352 static void 353 grace_alarm_handler(int sig) 354 { 355 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 356 kill(pmonitor->m_pid, SIGALRM); 357 358 /* Log error and exit. */ 359 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 360 } 361 362 /* 363 * Signal handler for the key regeneration alarm. Note that this 364 * alarm only occurs in the daemon waiting for connections, and it does not 365 * do anything with the private key or random state before forking. 366 * Thus there should be no concurrency control/asynchronous execution 367 * problems. 368 */ 369 static void 370 generate_ephemeral_server_key(void) 371 { 372 verbose("Generating %s%d bit RSA key.", 373 sensitive_data.server_key ? "new " : "", options.server_key_bits); 374 if (sensitive_data.server_key != NULL) 375 key_free(sensitive_data.server_key); 376 sensitive_data.server_key = key_generate(KEY_RSA1, 377 options.server_key_bits); 378 verbose("RSA key generation complete."); 379 380 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 381 arc4random_stir(); 382 } 383 384 /*ARGSUSED*/ 385 static void 386 key_regeneration_alarm(int sig) 387 { 388 int save_errno = errno; 389 390 signal(SIGALRM, SIG_DFL); 391 errno = save_errno; 392 key_do_regen = 1; 393 } 394 395 static void 396 sshd_exchange_identification(int sock_in, int sock_out) 397 { 398 u_int i; 399 int mismatch; 400 int remote_major, remote_minor; 401 int major, minor; 402 char *s, *newline = "\n"; 403 char buf[256]; /* Must not be larger than remote_version. */ 404 char remote_version[256]; /* Must be at least as big as buf. */ 405 406 if ((options.protocol & SSH_PROTO_1) && 407 (options.protocol & SSH_PROTO_2)) { 408 major = PROTOCOL_MAJOR_1; 409 minor = 99; 410 } else if (options.protocol & SSH_PROTO_2) { 411 major = PROTOCOL_MAJOR_2; 412 minor = PROTOCOL_MINOR_2; 413 newline = "\r\n"; 414 } else { 415 major = PROTOCOL_MAJOR_1; 416 minor = PROTOCOL_MINOR_1; 417 } 418 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor, 419 SSH_VERSION, newline); 420 server_version_string = xstrdup(buf); 421 422 /* Send our protocol version identification. */ 423 if (atomicio(vwrite, sock_out, server_version_string, 424 strlen(server_version_string)) 425 != strlen(server_version_string)) { 426 logit("Could not write ident string to %s", get_remote_ipaddr()); 427 cleanup_exit(255); 428 } 429 430 /* Read other sides version identification. */ 431 memset(buf, 0, sizeof(buf)); 432 for (i = 0; i < sizeof(buf) - 1; i++) { 433 if (atomicio(read, sock_in, &buf[i], 1) != 1) { 434 logit("Did not receive identification string from %s", 435 get_remote_ipaddr()); 436 cleanup_exit(255); 437 } 438 if (buf[i] == '\r') { 439 buf[i] = 0; 440 /* Kludge for F-Secure Macintosh < 1.0.2 */ 441 if (i == 12 && 442 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 443 break; 444 continue; 445 } 446 if (buf[i] == '\n') { 447 buf[i] = 0; 448 break; 449 } 450 } 451 buf[sizeof(buf) - 1] = 0; 452 client_version_string = xstrdup(buf); 453 454 /* 455 * Check that the versions match. In future this might accept 456 * several versions and set appropriate flags to handle them. 457 */ 458 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 459 &remote_major, &remote_minor, remote_version) != 3) { 460 s = "Protocol mismatch.\n"; 461 (void) atomicio(vwrite, sock_out, s, strlen(s)); 462 close(sock_in); 463 close(sock_out); 464 logit("Bad protocol version identification '%.100s' from %s", 465 client_version_string, get_remote_ipaddr()); 466 cleanup_exit(255); 467 } 468 debug("Client protocol version %d.%d; client software version %.100s", 469 remote_major, remote_minor, remote_version); 470 471 compat_datafellows(remote_version); 472 473 if (datafellows & SSH_BUG_PROBE) { 474 logit("probed from %s with %s. Don't panic.", 475 get_remote_ipaddr(), client_version_string); 476 cleanup_exit(255); 477 } 478 479 if (datafellows & SSH_BUG_SCANNER) { 480 logit("scanned from %s with %s. Don't panic.", 481 get_remote_ipaddr(), client_version_string); 482 cleanup_exit(255); 483 } 484 485 mismatch = 0; 486 switch (remote_major) { 487 case 1: 488 if (remote_minor == 99) { 489 if (options.protocol & SSH_PROTO_2) 490 enable_compat20(); 491 else 492 mismatch = 1; 493 break; 494 } 495 if (!(options.protocol & SSH_PROTO_1)) { 496 mismatch = 1; 497 break; 498 } 499 if (remote_minor < 3) { 500 packet_disconnect("Your ssh version is too old and " 501 "is no longer supported. Please install a newer version."); 502 } else if (remote_minor == 3) { 503 /* note that this disables agent-forwarding */ 504 enable_compat13(); 505 } 506 break; 507 case 2: 508 if (options.protocol & SSH_PROTO_2) { 509 enable_compat20(); 510 break; 511 } 512 /* FALLTHROUGH */ 513 default: 514 mismatch = 1; 515 break; 516 } 517 chop(server_version_string); 518 debug("Local version string %.200s", server_version_string); 519 520 if (mismatch) { 521 s = "Protocol major versions differ.\n"; 522 (void) atomicio(vwrite, sock_out, s, strlen(s)); 523 close(sock_in); 524 close(sock_out); 525 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 526 get_remote_ipaddr(), 527 server_version_string, client_version_string); 528 cleanup_exit(255); 529 } 530 } 531 532 /* Destroy the host and server keys. They will no longer be needed. */ 533 void 534 destroy_sensitive_data(void) 535 { 536 int i; 537 538 if (sensitive_data.server_key) { 539 key_free(sensitive_data.server_key); 540 sensitive_data.server_key = NULL; 541 } 542 for (i = 0; i < options.num_host_key_files; i++) { 543 if (sensitive_data.host_keys[i]) { 544 key_free(sensitive_data.host_keys[i]); 545 sensitive_data.host_keys[i] = NULL; 546 } 547 } 548 sensitive_data.ssh1_host_key = NULL; 549 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); 550 } 551 552 /* Demote private to public keys for network child */ 553 void 554 demote_sensitive_data(void) 555 { 556 Key *tmp; 557 int i; 558 559 if (sensitive_data.server_key) { 560 tmp = key_demote(sensitive_data.server_key); 561 key_free(sensitive_data.server_key); 562 sensitive_data.server_key = tmp; 563 } 564 565 for (i = 0; i < options.num_host_key_files; i++) { 566 if (sensitive_data.host_keys[i]) { 567 tmp = key_demote(sensitive_data.host_keys[i]); 568 key_free(sensitive_data.host_keys[i]); 569 sensitive_data.host_keys[i] = tmp; 570 if (tmp->type == KEY_RSA1) 571 sensitive_data.ssh1_host_key = tmp; 572 } 573 } 574 575 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 576 } 577 578 static void 579 privsep_preauth_child(void) 580 { 581 u_int32_t rnd[256]; 582 gid_t gidset[1]; 583 584 /* Enable challenge-response authentication for privilege separation */ 585 privsep_challenge_enable(); 586 587 arc4random_stir(); 588 arc4random_buf(rnd, sizeof(rnd)); 589 RAND_seed(rnd, sizeof(rnd)); 590 591 /* Demote the private keys to public keys. */ 592 demote_sensitive_data(); 593 594 /* Change our root directory */ 595 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 596 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 597 strerror(errno)); 598 if (chdir("/") == -1) 599 fatal("chdir(\"/\"): %s", strerror(errno)); 600 601 /* Drop our privileges */ 602 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 603 (u_int)privsep_pw->pw_gid); 604 #if 0 605 /* XXX not ready, too heavy after chroot */ 606 do_setusercontext(privsep_pw); 607 #else 608 gidset[0] = privsep_pw->pw_gid; 609 if (setgroups(1, gidset) < 0) 610 fatal("setgroups: %.100s", strerror(errno)); 611 permanently_set_uid(privsep_pw); 612 #endif 613 } 614 615 static int 616 privsep_preauth(Authctxt *authctxt) 617 { 618 int status; 619 pid_t pid; 620 621 /* Set up unprivileged child process to deal with network data */ 622 pmonitor = monitor_init(); 623 /* Store a pointer to the kex for later rekeying */ 624 pmonitor->m_pkex = &xxx_kex; 625 626 pid = fork(); 627 if (pid == -1) { 628 fatal("fork of unprivileged child failed"); 629 } else if (pid != 0) { 630 debug2("Network child is on pid %ld", (long)pid); 631 632 close(pmonitor->m_recvfd); 633 pmonitor->m_pid = pid; 634 monitor_child_preauth(authctxt, pmonitor); 635 close(pmonitor->m_sendfd); 636 637 /* Sync memory */ 638 monitor_sync(pmonitor); 639 640 /* Wait for the child's exit status */ 641 while (waitpid(pid, &status, 0) < 0) 642 if (errno != EINTR) 643 break; 644 return (1); 645 } else { 646 /* child */ 647 648 close(pmonitor->m_sendfd); 649 650 /* Demote the child */ 651 if (getuid() == 0 || geteuid() == 0) 652 privsep_preauth_child(); 653 setproctitle("%s", "[net]"); 654 } 655 return (0); 656 } 657 658 static void 659 privsep_postauth(Authctxt *authctxt) 660 { 661 u_int32_t rnd[256]; 662 663 #ifdef DISABLE_FD_PASSING 664 if (1) { 665 #else 666 if (authctxt->pw->pw_uid == 0 || options.use_login) { 667 #endif 668 /* File descriptor passing is broken or root login */ 669 use_privsep = 0; 670 goto skip; 671 } 672 673 /* New socket pair */ 674 monitor_reinit(pmonitor); 675 676 pmonitor->m_pid = fork(); 677 if (pmonitor->m_pid == -1) 678 fatal("fork of unprivileged child failed"); 679 else if (pmonitor->m_pid != 0) { 680 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 681 close(pmonitor->m_recvfd); 682 buffer_clear(&loginmsg); 683 monitor_child_postauth(pmonitor); 684 685 /* NEVERREACHED */ 686 exit(0); 687 } 688 689 close(pmonitor->m_sendfd); 690 691 /* Demote the private keys to public keys. */ 692 demote_sensitive_data(); 693 694 arc4random_stir(); 695 arc4random_buf(rnd, sizeof(rnd)); 696 RAND_seed(rnd, sizeof(rnd)); 697 698 /* Drop privileges */ 699 do_setusercontext(authctxt->pw); 700 701 skip: 702 /* It is safe now to apply the key state */ 703 monitor_apply_keystate(pmonitor); 704 705 /* 706 * Tell the packet layer that authentication was successful, since 707 * this information is not part of the key state. 708 */ 709 packet_set_authenticated(); 710 } 711 712 static char * 713 list_hostkey_types(void) 714 { 715 Buffer b; 716 const char *p; 717 char *ret; 718 int i; 719 720 buffer_init(&b); 721 for (i = 0; i < options.num_host_key_files; i++) { 722 Key *key = sensitive_data.host_keys[i]; 723 if (key == NULL) 724 continue; 725 switch (key->type) { 726 case KEY_RSA: 727 case KEY_DSA: 728 if (buffer_len(&b) > 0) 729 buffer_append(&b, ",", 1); 730 p = key_ssh_name(key); 731 buffer_append(&b, p, strlen(p)); 732 break; 733 } 734 } 735 buffer_append(&b, "\0", 1); 736 ret = xstrdup(buffer_ptr(&b)); 737 buffer_free(&b); 738 debug("list_hostkey_types: %s", ret); 739 return ret; 740 } 741 742 Key * 743 get_hostkey_by_type(int type) 744 { 745 int i; 746 747 for (i = 0; i < options.num_host_key_files; i++) { 748 Key *key = sensitive_data.host_keys[i]; 749 if (key != NULL && key->type == type) 750 return key; 751 } 752 return NULL; 753 } 754 755 Key * 756 get_hostkey_by_index(int ind) 757 { 758 if (ind < 0 || ind >= options.num_host_key_files) 759 return (NULL); 760 return (sensitive_data.host_keys[ind]); 761 } 762 763 int 764 get_hostkey_index(Key *key) 765 { 766 int i; 767 768 for (i = 0; i < options.num_host_key_files; i++) { 769 if (key == sensitive_data.host_keys[i]) 770 return (i); 771 } 772 return (-1); 773 } 774 775 /* 776 * returns 1 if connection should be dropped, 0 otherwise. 777 * dropping starts at connection #max_startups_begin with a probability 778 * of (max_startups_rate/100). the probability increases linearly until 779 * all connections are dropped for startups > max_startups 780 */ 781 static int 782 drop_connection(int startups) 783 { 784 int p, r; 785 786 if (startups < options.max_startups_begin) 787 return 0; 788 if (startups >= options.max_startups) 789 return 1; 790 if (options.max_startups_rate == 100) 791 return 1; 792 793 p = 100 - options.max_startups_rate; 794 p *= startups - options.max_startups_begin; 795 p /= options.max_startups - options.max_startups_begin; 796 p += options.max_startups_rate; 797 r = arc4random_uniform(100); 798 799 debug("drop_connection: p %d, r %d", p, r); 800 return (r < p) ? 1 : 0; 801 } 802 803 static void 804 usage(void) 805 { 806 fprintf(stderr, "%s, %s\n", 807 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); 808 fprintf(stderr, 809 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-f config_file]\n" 810 " [-g login_grace_time] [-h host_key_file] [-k key_gen_time]\n" 811 " [-o option] [-p port] [-u len]\n" 812 ); 813 exit(1); 814 } 815 816 static void 817 send_rexec_state(int fd, Buffer *conf) 818 { 819 Buffer m; 820 821 debug3("%s: entering fd = %d config len %d", __func__, fd, 822 buffer_len(conf)); 823 824 /* 825 * Protocol from reexec master to child: 826 * string configuration 827 * u_int ephemeral_key_follows 828 * bignum e (only if ephemeral_key_follows == 1) 829 * bignum n " 830 * bignum d " 831 * bignum iqmp " 832 * bignum p " 833 * bignum q " 834 * string rngseed (only if OpenSSL is not self-seeded) 835 */ 836 buffer_init(&m); 837 buffer_put_cstring(&m, buffer_ptr(conf)); 838 839 if (sensitive_data.server_key != NULL && 840 sensitive_data.server_key->type == KEY_RSA1) { 841 buffer_put_int(&m, 1); 842 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 843 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 844 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 845 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 846 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 847 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 848 } else 849 buffer_put_int(&m, 0); 850 851 #ifndef OPENSSL_PRNG_ONLY 852 rexec_send_rng_seed(&m); 853 #endif 854 855 if (ssh_msg_send(fd, 0, &m) == -1) 856 fatal("%s: ssh_msg_send failed", __func__); 857 858 buffer_free(&m); 859 860 debug3("%s: done", __func__); 861 } 862 863 static void 864 recv_rexec_state(int fd, Buffer *conf) 865 { 866 Buffer m; 867 char *cp; 868 u_int len; 869 870 debug3("%s: entering fd = %d", __func__, fd); 871 872 buffer_init(&m); 873 874 if (ssh_msg_recv(fd, &m) == -1) 875 fatal("%s: ssh_msg_recv failed", __func__); 876 if (buffer_get_char(&m) != 0) 877 fatal("%s: rexec version mismatch", __func__); 878 879 cp = buffer_get_string(&m, &len); 880 if (conf != NULL) 881 buffer_append(conf, cp, len + 1); 882 xfree(cp); 883 884 if (buffer_get_int(&m)) { 885 if (sensitive_data.server_key != NULL) 886 key_free(sensitive_data.server_key); 887 sensitive_data.server_key = key_new_private(KEY_RSA1); 888 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 889 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 890 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 891 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 892 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 893 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 894 rsa_generate_additional_parameters( 895 sensitive_data.server_key->rsa); 896 } 897 898 #ifndef OPENSSL_PRNG_ONLY 899 rexec_recv_rng_seed(&m); 900 #endif 901 902 buffer_free(&m); 903 904 debug3("%s: done", __func__); 905 } 906 907 /* Accept a connection from inetd */ 908 static void 909 server_accept_inetd(int *sock_in, int *sock_out) 910 { 911 int fd; 912 913 startup_pipe = -1; 914 if (rexeced_flag) { 915 close(REEXEC_CONFIG_PASS_FD); 916 *sock_in = *sock_out = dup(STDIN_FILENO); 917 if (!debug_flag) { 918 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 919 close(REEXEC_STARTUP_PIPE_FD); 920 } 921 } else { 922 *sock_in = dup(STDIN_FILENO); 923 *sock_out = dup(STDOUT_FILENO); 924 } 925 /* 926 * We intentionally do not close the descriptors 0, 1, and 2 927 * as our code for setting the descriptors won't work if 928 * ttyfd happens to be one of those. 929 */ 930 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 931 dup2(fd, STDIN_FILENO); 932 dup2(fd, STDOUT_FILENO); 933 if (fd > STDOUT_FILENO) 934 close(fd); 935 } 936 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 937 } 938 939 /* 940 * Listen for TCP connections 941 */ 942 static void 943 server_listen(void) 944 { 945 int ret, listen_sock, on = 1; 946 struct addrinfo *ai; 947 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 948 949 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 950 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 951 continue; 952 if (num_listen_socks >= MAX_LISTEN_SOCKS) 953 fatal("Too many listen sockets. " 954 "Enlarge MAX_LISTEN_SOCKS"); 955 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 956 ntop, sizeof(ntop), strport, sizeof(strport), 957 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 958 error("getnameinfo failed: %.100s", 959 ssh_gai_strerror(ret)); 960 continue; 961 } 962 /* Create socket for listening. */ 963 listen_sock = socket(ai->ai_family, ai->ai_socktype, 964 ai->ai_protocol); 965 if (listen_sock < 0) { 966 /* kernel may not support ipv6 */ 967 verbose("socket: %.100s", strerror(errno)); 968 continue; 969 } 970 if (set_nonblock(listen_sock) == -1) { 971 close(listen_sock); 972 continue; 973 } 974 /* 975 * Set socket options. 976 * Allow local port reuse in TIME_WAIT. 977 */ 978 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 979 &on, sizeof(on)) == -1) 980 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 981 982 #ifdef IPV6_V6ONLY 983 /* Only communicate in IPv6 over AF_INET6 sockets. */ 984 if (ai->ai_family == AF_INET6) { 985 if (setsockopt(listen_sock, IPPROTO_IPV6, IPV6_V6ONLY, 986 &on, sizeof(on)) == -1) 987 error("setsockopt IPV6_V6ONLY: %s", 988 strerror(errno)); 989 } 990 #endif 991 992 debug("Bind to port %s on %s.", strport, ntop); 993 994 /* Bind the socket to the desired port. */ 995 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 996 error("Bind to port %s on %s failed: %.200s.", 997 strport, ntop, strerror(errno)); 998 close(listen_sock); 999 continue; 1000 } 1001 listen_socks[num_listen_socks] = listen_sock; 1002 num_listen_socks++; 1003 1004 /* Start listening on the port. */ 1005 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1006 fatal("listen on [%s]:%s: %.100s", 1007 ntop, strport, strerror(errno)); 1008 logit("Server listening on %s port %s.", ntop, strport); 1009 } 1010 freeaddrinfo(options.listen_addrs); 1011 1012 if (!num_listen_socks) 1013 fatal("Cannot bind any address."); 1014 } 1015 1016 /* 1017 * The main TCP accept loop. Note that, for the non-debug case, returns 1018 * from this function are in a forked subprocess. 1019 */ 1020 static void 1021 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1022 { 1023 fd_set *fdset; 1024 int i, j, ret, maxfd; 1025 int key_used = 0, startups = 0; 1026 int startup_p[2] = { -1 , -1 }; 1027 struct sockaddr_storage from; 1028 socklen_t fromlen; 1029 pid_t pid; 1030 1031 /* setup fd set for accept */ 1032 fdset = NULL; 1033 maxfd = 0; 1034 for (i = 0; i < num_listen_socks; i++) 1035 if (listen_socks[i] > maxfd) 1036 maxfd = listen_socks[i]; 1037 /* pipes connected to unauthenticated childs */ 1038 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1039 for (i = 0; i < options.max_startups; i++) 1040 startup_pipes[i] = -1; 1041 1042 /* 1043 * Stay listening for connections until the system crashes or 1044 * the daemon is killed with a signal. 1045 */ 1046 for (;;) { 1047 if (received_sighup) 1048 sighup_restart(); 1049 if (fdset != NULL) 1050 xfree(fdset); 1051 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1052 sizeof(fd_mask)); 1053 1054 for (i = 0; i < num_listen_socks; i++) 1055 FD_SET(listen_socks[i], fdset); 1056 for (i = 0; i < options.max_startups; i++) 1057 if (startup_pipes[i] != -1) 1058 FD_SET(startup_pipes[i], fdset); 1059 1060 /* Wait in select until there is a connection. */ 1061 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1062 if (ret < 0 && errno != EINTR) 1063 error("select: %.100s", strerror(errno)); 1064 if (received_sigterm) { 1065 logit("Received signal %d; terminating.", 1066 (int) received_sigterm); 1067 close_listen_socks(); 1068 unlink(options.pid_file); 1069 exit(255); 1070 } 1071 if (key_used && key_do_regen) { 1072 generate_ephemeral_server_key(); 1073 key_used = 0; 1074 key_do_regen = 0; 1075 } 1076 if (ret < 0) 1077 continue; 1078 1079 for (i = 0; i < options.max_startups; i++) 1080 if (startup_pipes[i] != -1 && 1081 FD_ISSET(startup_pipes[i], fdset)) { 1082 /* 1083 * the read end of the pipe is ready 1084 * if the child has closed the pipe 1085 * after successful authentication 1086 * or if the child has died 1087 */ 1088 close(startup_pipes[i]); 1089 startup_pipes[i] = -1; 1090 startups--; 1091 } 1092 for (i = 0; i < num_listen_socks; i++) { 1093 if (!FD_ISSET(listen_socks[i], fdset)) 1094 continue; 1095 fromlen = sizeof(from); 1096 *newsock = accept(listen_socks[i], 1097 (struct sockaddr *)&from, &fromlen); 1098 if (*newsock < 0) { 1099 if (errno != EINTR && errno != EAGAIN && 1100 errno != EWOULDBLOCK) 1101 error("accept: %.100s", strerror(errno)); 1102 continue; 1103 } 1104 if (unset_nonblock(*newsock) == -1) { 1105 close(*newsock); 1106 continue; 1107 } 1108 if (drop_connection(startups) == 1) { 1109 debug("drop connection #%d", startups); 1110 close(*newsock); 1111 continue; 1112 } 1113 if (pipe(startup_p) == -1) { 1114 close(*newsock); 1115 continue; 1116 } 1117 1118 if (rexec_flag && socketpair(AF_UNIX, 1119 SOCK_STREAM, 0, config_s) == -1) { 1120 error("reexec socketpair: %s", 1121 strerror(errno)); 1122 close(*newsock); 1123 close(startup_p[0]); 1124 close(startup_p[1]); 1125 continue; 1126 } 1127 1128 for (j = 0; j < options.max_startups; j++) 1129 if (startup_pipes[j] == -1) { 1130 startup_pipes[j] = startup_p[0]; 1131 if (maxfd < startup_p[0]) 1132 maxfd = startup_p[0]; 1133 startups++; 1134 break; 1135 } 1136 1137 /* 1138 * Got connection. Fork a child to handle it, unless 1139 * we are in debugging mode. 1140 */ 1141 if (debug_flag) { 1142 /* 1143 * In debugging mode. Close the listening 1144 * socket, and start processing the 1145 * connection without forking. 1146 */ 1147 debug("Server will not fork when running in debugging mode."); 1148 close_listen_socks(); 1149 *sock_in = *newsock; 1150 *sock_out = *newsock; 1151 close(startup_p[0]); 1152 close(startup_p[1]); 1153 startup_pipe = -1; 1154 pid = getpid(); 1155 if (rexec_flag) { 1156 send_rexec_state(config_s[0], 1157 &cfg); 1158 close(config_s[0]); 1159 } 1160 break; 1161 } 1162 1163 /* 1164 * Normal production daemon. Fork, and have 1165 * the child process the connection. The 1166 * parent continues listening. 1167 */ 1168 platform_pre_fork(); 1169 if ((pid = fork()) == 0) { 1170 /* 1171 * Child. Close the listening and 1172 * max_startup sockets. Start using 1173 * the accepted socket. Reinitialize 1174 * logging (since our pid has changed). 1175 * We break out of the loop to handle 1176 * the connection. 1177 */ 1178 platform_post_fork_child(); 1179 startup_pipe = startup_p[1]; 1180 close_startup_pipes(); 1181 close_listen_socks(); 1182 *sock_in = *newsock; 1183 *sock_out = *newsock; 1184 log_init(__progname, 1185 options.log_level, 1186 options.log_facility, 1187 log_stderr); 1188 if (rexec_flag) 1189 close(config_s[0]); 1190 break; 1191 } 1192 1193 /* Parent. Stay in the loop. */ 1194 platform_post_fork_parent(pid); 1195 if (pid < 0) 1196 error("fork: %.100s", strerror(errno)); 1197 else 1198 debug("Forked child %ld.", (long)pid); 1199 1200 close(startup_p[1]); 1201 1202 if (rexec_flag) { 1203 send_rexec_state(config_s[0], &cfg); 1204 close(config_s[0]); 1205 close(config_s[1]); 1206 } 1207 1208 /* 1209 * Mark that the key has been used (it 1210 * was "given" to the child). 1211 */ 1212 if ((options.protocol & SSH_PROTO_1) && 1213 key_used == 0) { 1214 /* Schedule server key regeneration alarm. */ 1215 signal(SIGALRM, key_regeneration_alarm); 1216 alarm(options.key_regeneration_time); 1217 key_used = 1; 1218 } 1219 1220 close(*newsock); 1221 1222 /* 1223 * Ensure that our random state differs 1224 * from that of the child 1225 */ 1226 arc4random_stir(); 1227 } 1228 1229 /* child process check (or debug mode) */ 1230 if (num_listen_socks < 0) 1231 break; 1232 } 1233 } 1234 1235 1236 /* 1237 * Main program for the daemon. 1238 */ 1239 int 1240 main(int ac, char **av) 1241 { 1242 extern char *optarg; 1243 extern int optind; 1244 int opt, i, on = 1; 1245 int sock_in = -1, sock_out = -1, newsock = -1; 1246 const char *remote_ip; 1247 char *test_user = NULL, *test_host = NULL, *test_addr = NULL; 1248 int remote_port; 1249 char *line, *p, *cp; 1250 int config_s[2] = { -1 , -1 }; 1251 u_int64_t ibytes, obytes; 1252 mode_t new_umask; 1253 Key *key; 1254 Authctxt *authctxt; 1255 1256 #ifdef HAVE_SECUREWARE 1257 (void)set_auth_parameters(ac, av); 1258 #endif 1259 __progname = ssh_get_progname(av[0]); 1260 init_rng(); 1261 1262 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1263 saved_argc = ac; 1264 rexec_argc = ac; 1265 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1266 for (i = 0; i < ac; i++) 1267 saved_argv[i] = xstrdup(av[i]); 1268 saved_argv[i] = NULL; 1269 1270 #ifndef HAVE_SETPROCTITLE 1271 /* Prepare for later setproctitle emulation */ 1272 compat_init_setproctitle(ac, av); 1273 av = saved_argv; 1274 #endif 1275 1276 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1277 debug("setgroups(): %.200s", strerror(errno)); 1278 1279 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1280 sanitise_stdfd(); 1281 1282 /* Initialize configuration options to their default values. */ 1283 initialize_server_options(&options); 1284 1285 /* Parse command-line arguments. */ 1286 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) { 1287 switch (opt) { 1288 case '4': 1289 options.address_family = AF_INET; 1290 break; 1291 case '6': 1292 options.address_family = AF_INET6; 1293 break; 1294 case 'f': 1295 config_file_name = optarg; 1296 break; 1297 case 'd': 1298 if (debug_flag == 0) { 1299 debug_flag = 1; 1300 options.log_level = SYSLOG_LEVEL_DEBUG1; 1301 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1302 options.log_level++; 1303 break; 1304 case 'D': 1305 no_daemon_flag = 1; 1306 break; 1307 case 'e': 1308 log_stderr = 1; 1309 break; 1310 case 'i': 1311 inetd_flag = 1; 1312 break; 1313 case 'r': 1314 rexec_flag = 0; 1315 break; 1316 case 'R': 1317 rexeced_flag = 1; 1318 inetd_flag = 1; 1319 break; 1320 case 'Q': 1321 /* ignored */ 1322 break; 1323 case 'q': 1324 options.log_level = SYSLOG_LEVEL_QUIET; 1325 break; 1326 case 'b': 1327 options.server_key_bits = (int)strtonum(optarg, 256, 1328 32768, NULL); 1329 break; 1330 case 'p': 1331 options.ports_from_cmdline = 1; 1332 if (options.num_ports >= MAX_PORTS) { 1333 fprintf(stderr, "too many ports.\n"); 1334 exit(1); 1335 } 1336 options.ports[options.num_ports++] = a2port(optarg); 1337 if (options.ports[options.num_ports-1] <= 0) { 1338 fprintf(stderr, "Bad port number.\n"); 1339 exit(1); 1340 } 1341 break; 1342 case 'g': 1343 if ((options.login_grace_time = convtime(optarg)) == -1) { 1344 fprintf(stderr, "Invalid login grace time.\n"); 1345 exit(1); 1346 } 1347 break; 1348 case 'k': 1349 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1350 fprintf(stderr, "Invalid key regeneration interval.\n"); 1351 exit(1); 1352 } 1353 break; 1354 case 'h': 1355 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1356 fprintf(stderr, "too many host keys.\n"); 1357 exit(1); 1358 } 1359 options.host_key_files[options.num_host_key_files++] = optarg; 1360 break; 1361 case 't': 1362 test_flag = 1; 1363 break; 1364 case 'T': 1365 test_flag = 2; 1366 break; 1367 case 'C': 1368 cp = optarg; 1369 while ((p = strsep(&cp, ",")) && *p != '\0') { 1370 if (strncmp(p, "addr=", 5) == 0) 1371 test_addr = xstrdup(p + 5); 1372 else if (strncmp(p, "host=", 5) == 0) 1373 test_host = xstrdup(p + 5); 1374 else if (strncmp(p, "user=", 5) == 0) 1375 test_user = xstrdup(p + 5); 1376 else { 1377 fprintf(stderr, "Invalid test " 1378 "mode specification %s\n", p); 1379 exit(1); 1380 } 1381 } 1382 break; 1383 case 'u': 1384 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1385 if (utmp_len > MAXHOSTNAMELEN) { 1386 fprintf(stderr, "Invalid utmp length.\n"); 1387 exit(1); 1388 } 1389 break; 1390 case 'o': 1391 line = xstrdup(optarg); 1392 if (process_server_config_line(&options, line, 1393 "command-line", 0, NULL, NULL, NULL, NULL) != 0) 1394 exit(1); 1395 xfree(line); 1396 break; 1397 case '?': 1398 default: 1399 usage(); 1400 break; 1401 } 1402 } 1403 if (rexeced_flag || inetd_flag) 1404 rexec_flag = 0; 1405 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1406 fatal("sshd re-exec requires execution with an absolute path"); 1407 if (rexeced_flag) 1408 closefrom(REEXEC_MIN_FREE_FD); 1409 else 1410 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1411 1412 SSLeay_add_all_algorithms(); 1413 1414 /* 1415 * Force logging to stderr until we have loaded the private host 1416 * key (unless started from inetd) 1417 */ 1418 log_init(__progname, 1419 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1420 SYSLOG_LEVEL_INFO : options.log_level, 1421 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1422 SYSLOG_FACILITY_AUTH : options.log_facility, 1423 log_stderr || !inetd_flag); 1424 1425 /* 1426 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1427 * root's environment 1428 */ 1429 if (getenv("KRB5CCNAME") != NULL) 1430 unsetenv("KRB5CCNAME"); 1431 1432 #ifdef _UNICOS 1433 /* Cray can define user privs drop all privs now! 1434 * Not needed on PRIV_SU systems! 1435 */ 1436 drop_cray_privs(); 1437 #endif 1438 1439 sensitive_data.server_key = NULL; 1440 sensitive_data.ssh1_host_key = NULL; 1441 sensitive_data.have_ssh1_key = 0; 1442 sensitive_data.have_ssh2_key = 0; 1443 1444 /* 1445 * If we're doing an extended config test, make sure we have all of 1446 * the parameters we need. If we're not doing an extended test, 1447 * do not silently ignore connection test params. 1448 */ 1449 if (test_flag >= 2 && 1450 (test_user != NULL || test_host != NULL || test_addr != NULL) 1451 && (test_user == NULL || test_host == NULL || test_addr == NULL)) 1452 fatal("user, host and addr are all required when testing " 1453 "Match configs"); 1454 if (test_flag < 2 && (test_user != NULL || test_host != NULL || 1455 test_addr != NULL)) 1456 fatal("Config test connection parameter (-C) provided without " 1457 "test mode (-T)"); 1458 1459 /* Fetch our configuration */ 1460 buffer_init(&cfg); 1461 if (rexeced_flag) 1462 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1463 else 1464 load_server_config(config_file_name, &cfg); 1465 1466 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1467 &cfg, NULL, NULL, NULL); 1468 1469 seed_rng(); 1470 1471 /* Fill in default values for those options not explicitly set. */ 1472 fill_default_server_options(&options); 1473 1474 /* challenge-response is implemented via keyboard interactive */ 1475 if (options.challenge_response_authentication) 1476 options.kbd_interactive_authentication = 1; 1477 1478 /* set default channel AF */ 1479 channel_set_af(options.address_family); 1480 1481 /* Check that there are no remaining arguments. */ 1482 if (optind < ac) { 1483 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1484 exit(1); 1485 } 1486 1487 debug("sshd version %.100s", SSH_RELEASE); 1488 1489 /* Store privilege separation user for later use if required. */ 1490 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1491 if (use_privsep || options.kerberos_authentication) 1492 fatal("Privilege separation user %s does not exist", 1493 SSH_PRIVSEP_USER); 1494 } else { 1495 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd)); 1496 privsep_pw = pwcopy(privsep_pw); 1497 xfree(privsep_pw->pw_passwd); 1498 privsep_pw->pw_passwd = xstrdup("*"); 1499 } 1500 endpwent(); 1501 1502 /* load private host keys */ 1503 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1504 sizeof(Key *)); 1505 for (i = 0; i < options.num_host_key_files; i++) 1506 sensitive_data.host_keys[i] = NULL; 1507 1508 for (i = 0; i < options.num_host_key_files; i++) { 1509 key = key_load_private(options.host_key_files[i], "", NULL); 1510 if (key && blacklisted_key(key)) { 1511 char *fp; 1512 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 1513 if (options.permit_blacklisted_keys) 1514 error("Host key %s blacklisted (see " 1515 "ssh-vulnkey(1)); continuing anyway", fp); 1516 else 1517 error("Host key %s blacklisted (see " 1518 "ssh-vulnkey(1))", fp); 1519 xfree(fp); 1520 if (!options.permit_blacklisted_keys) { 1521 sensitive_data.host_keys[i] = NULL; 1522 continue; 1523 } 1524 } 1525 sensitive_data.host_keys[i] = key; 1526 if (key == NULL) { 1527 error("Could not load host key: %s", 1528 options.host_key_files[i]); 1529 sensitive_data.host_keys[i] = NULL; 1530 continue; 1531 } 1532 switch (key->type) { 1533 case KEY_RSA1: 1534 sensitive_data.ssh1_host_key = key; 1535 sensitive_data.have_ssh1_key = 1; 1536 break; 1537 case KEY_RSA: 1538 case KEY_DSA: 1539 sensitive_data.have_ssh2_key = 1; 1540 break; 1541 } 1542 debug("private host key: #%d type %d %s", i, key->type, 1543 key_type(key)); 1544 } 1545 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1546 logit("Disabling protocol version 1. Could not load host key"); 1547 options.protocol &= ~SSH_PROTO_1; 1548 } 1549 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1550 logit("Disabling protocol version 2. Could not load host key"); 1551 options.protocol &= ~SSH_PROTO_2; 1552 } 1553 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1554 logit("sshd: no hostkeys available -- exiting."); 1555 exit(1); 1556 } 1557 1558 /* Check certain values for sanity. */ 1559 if (options.protocol & SSH_PROTO_1) { 1560 if (options.server_key_bits < 512 || 1561 options.server_key_bits > 32768) { 1562 fprintf(stderr, "Bad server key size.\n"); 1563 exit(1); 1564 } 1565 /* 1566 * Check that server and host key lengths differ sufficiently. This 1567 * is necessary to make double encryption work with rsaref. Oh, I 1568 * hate software patents. I dont know if this can go? Niels 1569 */ 1570 if (options.server_key_bits > 1571 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1572 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1573 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1574 SSH_KEY_BITS_RESERVED) { 1575 options.server_key_bits = 1576 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1577 SSH_KEY_BITS_RESERVED; 1578 debug("Forcing server key to %d bits to make it differ from host key.", 1579 options.server_key_bits); 1580 } 1581 } 1582 1583 if (use_privsep) { 1584 struct stat st; 1585 1586 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1587 (S_ISDIR(st.st_mode) == 0)) 1588 fatal("Missing privilege separation directory: %s", 1589 _PATH_PRIVSEP_CHROOT_DIR); 1590 1591 #ifdef HAVE_CYGWIN 1592 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1593 (st.st_uid != getuid () || 1594 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1595 #else 1596 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1597 #endif 1598 fatal("%s must be owned by root and not group or " 1599 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1600 } 1601 1602 if (test_flag > 1) { 1603 if (test_user != NULL && test_addr != NULL && test_host != NULL) 1604 parse_server_match_config(&options, test_user, 1605 test_host, test_addr); 1606 dump_config(&options); 1607 } 1608 1609 /* Configuration looks good, so exit if in test mode. */ 1610 if (test_flag) 1611 exit(0); 1612 1613 /* 1614 * Clear out any supplemental groups we may have inherited. This 1615 * prevents inadvertent creation of files with bad modes (in the 1616 * portable version at least, it's certainly possible for PAM 1617 * to create a file, and we can't control the code in every 1618 * module which might be used). 1619 */ 1620 if (setgroups(0, NULL) < 0) 1621 debug("setgroups() failed: %.200s", strerror(errno)); 1622 1623 if (rexec_flag) { 1624 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1625 for (i = 0; i < rexec_argc; i++) { 1626 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1627 rexec_argv[i] = saved_argv[i]; 1628 } 1629 rexec_argv[rexec_argc] = "-R"; 1630 rexec_argv[rexec_argc + 1] = NULL; 1631 } 1632 1633 /* Ensure that umask disallows at least group and world write */ 1634 new_umask = umask(0077) | 0022; 1635 (void) umask(new_umask); 1636 1637 /* Initialize the log (it is reinitialized below in case we forked). */ 1638 if (debug_flag && (!inetd_flag || rexeced_flag)) 1639 log_stderr = 1; 1640 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1641 1642 /* 1643 * If not in debugging mode, and not started from inetd, disconnect 1644 * from the controlling terminal, and fork. The original process 1645 * exits. 1646 */ 1647 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1648 #ifdef TIOCNOTTY 1649 int fd; 1650 #endif /* TIOCNOTTY */ 1651 if (daemon(0, 0) < 0) 1652 fatal("daemon() failed: %.200s", strerror(errno)); 1653 1654 /* Disconnect from the controlling tty. */ 1655 #ifdef TIOCNOTTY 1656 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1657 if (fd >= 0) { 1658 (void) ioctl(fd, TIOCNOTTY, NULL); 1659 close(fd); 1660 } 1661 #endif /* TIOCNOTTY */ 1662 } 1663 /* Reinitialize the log (because of the fork above). */ 1664 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1665 1666 /* Initialize the random number generator. */ 1667 arc4random_stir(); 1668 1669 /* Chdir to the root directory so that the current disk can be 1670 unmounted if desired. */ 1671 chdir("/"); 1672 1673 /* ignore SIGPIPE */ 1674 signal(SIGPIPE, SIG_IGN); 1675 1676 /* Get a connection, either from inetd or a listening TCP socket */ 1677 if (inetd_flag) { 1678 server_accept_inetd(&sock_in, &sock_out); 1679 } else { 1680 server_listen(); 1681 1682 if (options.protocol & SSH_PROTO_1) 1683 generate_ephemeral_server_key(); 1684 1685 signal(SIGHUP, sighup_handler); 1686 signal(SIGCHLD, main_sigchld_handler); 1687 signal(SIGTERM, sigterm_handler); 1688 signal(SIGQUIT, sigterm_handler); 1689 1690 /* 1691 * Write out the pid file after the sigterm handler 1692 * is setup and the listen sockets are bound 1693 */ 1694 if (!debug_flag) { 1695 FILE *f = fopen(options.pid_file, "w"); 1696 1697 if (f == NULL) { 1698 error("Couldn't create pid file \"%s\": %s", 1699 options.pid_file, strerror(errno)); 1700 } else { 1701 fprintf(f, "%ld\n", (long) getpid()); 1702 fclose(f); 1703 } 1704 } 1705 1706 /* Accept a connection and return in a forked child */ 1707 server_accept_loop(&sock_in, &sock_out, 1708 &newsock, config_s); 1709 } 1710 1711 /* This is the child processing a new connection. */ 1712 setproctitle("%s", "[accepted]"); 1713 1714 /* 1715 * Initialize the resolver. This may not happen automatically 1716 * before privsep chroot(). 1717 */ 1718 if ((_res.options & RES_INIT) == 0) { 1719 debug("res_init()"); 1720 res_init(); 1721 } 1722 1723 /* 1724 * Create a new session and process group since the 4.4BSD 1725 * setlogin() affects the entire process group. We don't 1726 * want the child to be able to affect the parent. 1727 */ 1728 #if !defined(SSHD_ACQUIRES_CTTY) 1729 /* 1730 * If setsid is called, on some platforms sshd will later acquire a 1731 * controlling terminal which will result in "could not set 1732 * controlling tty" errors. 1733 */ 1734 if (!debug_flag && !inetd_flag && setsid() < 0) 1735 error("setsid: %.100s", strerror(errno)); 1736 #endif 1737 1738 if (rexec_flag) { 1739 int fd; 1740 1741 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1742 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1743 dup2(newsock, STDIN_FILENO); 1744 dup2(STDIN_FILENO, STDOUT_FILENO); 1745 if (startup_pipe == -1) 1746 close(REEXEC_STARTUP_PIPE_FD); 1747 else 1748 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1749 1750 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1751 close(config_s[1]); 1752 if (startup_pipe != -1) 1753 close(startup_pipe); 1754 1755 execv(rexec_argv[0], rexec_argv); 1756 1757 /* Reexec has failed, fall back and continue */ 1758 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1759 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1760 log_init(__progname, options.log_level, 1761 options.log_facility, log_stderr); 1762 1763 /* Clean up fds */ 1764 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1765 close(config_s[1]); 1766 close(REEXEC_CONFIG_PASS_FD); 1767 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1768 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1769 dup2(fd, STDIN_FILENO); 1770 dup2(fd, STDOUT_FILENO); 1771 if (fd > STDERR_FILENO) 1772 close(fd); 1773 } 1774 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1775 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1776 } 1777 1778 /* 1779 * Disable the key regeneration alarm. We will not regenerate the 1780 * key since we are no longer in a position to give it to anyone. We 1781 * will not restart on SIGHUP since it no longer makes sense. 1782 */ 1783 alarm(0); 1784 signal(SIGALRM, SIG_DFL); 1785 signal(SIGHUP, SIG_DFL); 1786 signal(SIGTERM, SIG_DFL); 1787 signal(SIGQUIT, SIG_DFL); 1788 signal(SIGCHLD, SIG_DFL); 1789 signal(SIGINT, SIG_DFL); 1790 1791 /* 1792 * Register our connection. This turns encryption off because we do 1793 * not have a key. 1794 */ 1795 packet_set_connection(sock_in, sock_out); 1796 packet_set_server(); 1797 1798 /* Set SO_KEEPALIVE if requested. */ 1799 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 1800 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 1801 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1802 1803 if ((remote_port = get_remote_port()) < 0) { 1804 debug("get_remote_port failed"); 1805 cleanup_exit(255); 1806 } 1807 1808 /* 1809 * We use get_canonical_hostname with usedns = 0 instead of 1810 * get_remote_ipaddr here so IP options will be checked. 1811 */ 1812 (void) get_canonical_hostname(0); 1813 /* 1814 * The rest of the code depends on the fact that 1815 * get_remote_ipaddr() caches the remote ip, even if 1816 * the socket goes away. 1817 */ 1818 remote_ip = get_remote_ipaddr(); 1819 1820 #ifdef SSH_AUDIT_EVENTS 1821 audit_connection_from(remote_ip, remote_port); 1822 #endif 1823 #ifdef LIBWRAP 1824 allow_severity = options.log_facility|LOG_INFO; 1825 deny_severity = options.log_facility|LOG_WARNING; 1826 /* Check whether logins are denied from this host. */ 1827 if (packet_connection_is_on_socket()) { 1828 struct request_info req; 1829 1830 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 1831 fromhost(&req); 1832 1833 if (!hosts_access(&req)) { 1834 debug("Connection refused by tcp wrapper"); 1835 refuse(&req); 1836 /* NOTREACHED */ 1837 fatal("libwrap refuse returns"); 1838 } 1839 } 1840 #endif /* LIBWRAP */ 1841 1842 /* Log the connection. */ 1843 verbose("Connection from %.500s port %d", remote_ip, remote_port); 1844 1845 /* 1846 * We don't want to listen forever unless the other side 1847 * successfully authenticates itself. So we set up an alarm which is 1848 * cleared after successful authentication. A limit of zero 1849 * indicates no limit. Note that we don't set the alarm in debugging 1850 * mode; it is just annoying to have the server exit just when you 1851 * are about to discover the bug. 1852 */ 1853 signal(SIGALRM, grace_alarm_handler); 1854 if (!debug_flag) 1855 alarm(options.login_grace_time); 1856 1857 sshd_exchange_identification(sock_in, sock_out); 1858 1859 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 1860 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 1861 generate_ephemeral_server_key(); 1862 1863 packet_set_nonblocking(); 1864 1865 /* allocate authentication context */ 1866 authctxt = xcalloc(1, sizeof(*authctxt)); 1867 1868 authctxt->loginmsg = &loginmsg; 1869 1870 /* XXX global for cleanup, access from other modules */ 1871 the_authctxt = authctxt; 1872 1873 /* prepare buffer to collect messages to display to user after login */ 1874 buffer_init(&loginmsg); 1875 1876 if (use_privsep) 1877 if (privsep_preauth(authctxt) == 1) 1878 goto authenticated; 1879 1880 /* perform the key exchange */ 1881 /* authenticate user and start session */ 1882 if (compat20) { 1883 do_ssh2_kex(); 1884 do_authentication2(authctxt); 1885 } else { 1886 do_ssh1_kex(); 1887 do_authentication(authctxt); 1888 } 1889 /* 1890 * If we use privilege separation, the unprivileged child transfers 1891 * the current keystate and exits 1892 */ 1893 if (use_privsep) { 1894 mm_send_keystate(pmonitor); 1895 exit(0); 1896 } 1897 1898 authenticated: 1899 /* 1900 * Cancel the alarm we set to limit the time taken for 1901 * authentication. 1902 */ 1903 alarm(0); 1904 signal(SIGALRM, SIG_DFL); 1905 authctxt->authenticated = 1; 1906 if (startup_pipe != -1) { 1907 close(startup_pipe); 1908 startup_pipe = -1; 1909 } 1910 1911 #ifdef SSH_AUDIT_EVENTS 1912 audit_event(SSH_AUTH_SUCCESS); 1913 #endif 1914 1915 #ifdef GSSAPI 1916 if (options.gss_authentication) { 1917 temporarily_use_uid(authctxt->pw); 1918 ssh_gssapi_storecreds(); 1919 restore_uid(); 1920 } 1921 #endif 1922 #ifdef USE_PAM 1923 if (options.use_pam) { 1924 do_pam_setcred(1); 1925 do_pam_session(); 1926 } 1927 #endif 1928 1929 /* 1930 * In privilege separation, we fork another child and prepare 1931 * file descriptor passing. 1932 */ 1933 if (use_privsep) { 1934 privsep_postauth(authctxt); 1935 /* the monitor process [priv] will not return */ 1936 if (!compat20) 1937 destroy_sensitive_data(); 1938 } 1939 1940 packet_set_timeout(options.client_alive_interval, 1941 options.client_alive_count_max); 1942 1943 /* Start session. */ 1944 do_authenticated(authctxt); 1945 1946 /* The connection has been terminated. */ 1947 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 1948 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); 1949 verbose("Transferred: sent %llu, received %llu bytes", obytes, ibytes); 1950 1951 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 1952 1953 #ifdef USE_PAM 1954 if (options.use_pam) 1955 finish_pam(); 1956 #endif /* USE_PAM */ 1957 1958 #ifdef SSH_AUDIT_EVENTS 1959 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 1960 #endif 1961 1962 packet_close(); 1963 1964 if (use_privsep) 1965 mm_terminate(); 1966 1967 exit(0); 1968 } 1969 1970 /* 1971 * Decrypt session_key_int using our private server key and private host key 1972 * (key with larger modulus first). 1973 */ 1974 int 1975 ssh1_session_key(BIGNUM *session_key_int) 1976 { 1977 int rsafail = 0; 1978 1979 if (BN_cmp(sensitive_data.server_key->rsa->n, 1980 sensitive_data.ssh1_host_key->rsa->n) > 0) { 1981 /* Server key has bigger modulus. */ 1982 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 1983 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1984 SSH_KEY_BITS_RESERVED) { 1985 fatal("do_connection: %s: " 1986 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 1987 get_remote_ipaddr(), 1988 BN_num_bits(sensitive_data.server_key->rsa->n), 1989 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 1990 SSH_KEY_BITS_RESERVED); 1991 } 1992 if (rsa_private_decrypt(session_key_int, session_key_int, 1993 sensitive_data.server_key->rsa) <= 0) 1994 rsafail++; 1995 if (rsa_private_decrypt(session_key_int, session_key_int, 1996 sensitive_data.ssh1_host_key->rsa) <= 0) 1997 rsafail++; 1998 } else { 1999 /* Host key has bigger modulus (or they are equal). */ 2000 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2001 BN_num_bits(sensitive_data.server_key->rsa->n) + 2002 SSH_KEY_BITS_RESERVED) { 2003 fatal("do_connection: %s: " 2004 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2005 get_remote_ipaddr(), 2006 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2007 BN_num_bits(sensitive_data.server_key->rsa->n), 2008 SSH_KEY_BITS_RESERVED); 2009 } 2010 if (rsa_private_decrypt(session_key_int, session_key_int, 2011 sensitive_data.ssh1_host_key->rsa) < 0) 2012 rsafail++; 2013 if (rsa_private_decrypt(session_key_int, session_key_int, 2014 sensitive_data.server_key->rsa) < 0) 2015 rsafail++; 2016 } 2017 return (rsafail); 2018 } 2019 /* 2020 * SSH1 key exchange 2021 */ 2022 static void 2023 do_ssh1_kex(void) 2024 { 2025 int i, len; 2026 int rsafail = 0; 2027 BIGNUM *session_key_int; 2028 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2029 u_char cookie[8]; 2030 u_int cipher_type, auth_mask, protocol_flags; 2031 2032 /* 2033 * Generate check bytes that the client must send back in the user 2034 * packet in order for it to be accepted; this is used to defy ip 2035 * spoofing attacks. Note that this only works against somebody 2036 * doing IP spoofing from a remote machine; any machine on the local 2037 * network can still see outgoing packets and catch the random 2038 * cookie. This only affects rhosts authentication, and this is one 2039 * of the reasons why it is inherently insecure. 2040 */ 2041 arc4random_buf(cookie, sizeof(cookie)); 2042 2043 /* 2044 * Send our public key. We include in the packet 64 bits of random 2045 * data that must be matched in the reply in order to prevent IP 2046 * spoofing. 2047 */ 2048 packet_start(SSH_SMSG_PUBLIC_KEY); 2049 for (i = 0; i < 8; i++) 2050 packet_put_char(cookie[i]); 2051 2052 /* Store our public server RSA key. */ 2053 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2054 packet_put_bignum(sensitive_data.server_key->rsa->e); 2055 packet_put_bignum(sensitive_data.server_key->rsa->n); 2056 2057 /* Store our public host RSA key. */ 2058 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2059 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2060 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2061 2062 /* Put protocol flags. */ 2063 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2064 2065 /* Declare which ciphers we support. */ 2066 packet_put_int(cipher_mask_ssh1(0)); 2067 2068 /* Declare supported authentication types. */ 2069 auth_mask = 0; 2070 if (options.rhosts_rsa_authentication) 2071 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2072 if (options.rsa_authentication) 2073 auth_mask |= 1 << SSH_AUTH_RSA; 2074 if (options.challenge_response_authentication == 1) 2075 auth_mask |= 1 << SSH_AUTH_TIS; 2076 if (options.password_authentication) 2077 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2078 packet_put_int(auth_mask); 2079 2080 /* Send the packet and wait for it to be sent. */ 2081 packet_send(); 2082 packet_write_wait(); 2083 2084 debug("Sent %d bit server key and %d bit host key.", 2085 BN_num_bits(sensitive_data.server_key->rsa->n), 2086 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2087 2088 /* Read clients reply (cipher type and session key). */ 2089 packet_read_expect(SSH_CMSG_SESSION_KEY); 2090 2091 /* Get cipher type and check whether we accept this. */ 2092 cipher_type = packet_get_char(); 2093 2094 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2095 packet_disconnect("Warning: client selects unsupported cipher."); 2096 2097 /* Get check bytes from the packet. These must match those we 2098 sent earlier with the public key packet. */ 2099 for (i = 0; i < 8; i++) 2100 if (cookie[i] != packet_get_char()) 2101 packet_disconnect("IP Spoofing check bytes do not match."); 2102 2103 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2104 2105 /* Get the encrypted integer. */ 2106 if ((session_key_int = BN_new()) == NULL) 2107 fatal("do_ssh1_kex: BN_new failed"); 2108 packet_get_bignum(session_key_int); 2109 2110 protocol_flags = packet_get_int(); 2111 packet_set_protocol_flags(protocol_flags); 2112 packet_check_eom(); 2113 2114 /* Decrypt session_key_int using host/server keys */ 2115 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2116 2117 /* 2118 * Extract session key from the decrypted integer. The key is in the 2119 * least significant 256 bits of the integer; the first byte of the 2120 * key is in the highest bits. 2121 */ 2122 if (!rsafail) { 2123 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2124 len = BN_num_bytes(session_key_int); 2125 if (len < 0 || (u_int)len > sizeof(session_key)) { 2126 error("do_ssh1_kex: bad session key len from %s: " 2127 "session_key_int %d > sizeof(session_key) %lu", 2128 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2129 rsafail++; 2130 } else { 2131 memset(session_key, 0, sizeof(session_key)); 2132 BN_bn2bin(session_key_int, 2133 session_key + sizeof(session_key) - len); 2134 2135 derive_ssh1_session_id( 2136 sensitive_data.ssh1_host_key->rsa->n, 2137 sensitive_data.server_key->rsa->n, 2138 cookie, session_id); 2139 /* 2140 * Xor the first 16 bytes of the session key with the 2141 * session id. 2142 */ 2143 for (i = 0; i < 16; i++) 2144 session_key[i] ^= session_id[i]; 2145 } 2146 } 2147 if (rsafail) { 2148 int bytes = BN_num_bytes(session_key_int); 2149 u_char *buf = xmalloc(bytes); 2150 MD5_CTX md; 2151 2152 logit("do_connection: generating a fake encryption key"); 2153 BN_bn2bin(session_key_int, buf); 2154 MD5_Init(&md); 2155 MD5_Update(&md, buf, bytes); 2156 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2157 MD5_Final(session_key, &md); 2158 MD5_Init(&md); 2159 MD5_Update(&md, session_key, 16); 2160 MD5_Update(&md, buf, bytes); 2161 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2162 MD5_Final(session_key + 16, &md); 2163 memset(buf, 0, bytes); 2164 xfree(buf); 2165 for (i = 0; i < 16; i++) 2166 session_id[i] = session_key[i] ^ session_key[i + 16]; 2167 } 2168 /* Destroy the private and public keys. No longer. */ 2169 destroy_sensitive_data(); 2170 2171 if (use_privsep) 2172 mm_ssh1_session_id(session_id); 2173 2174 /* Destroy the decrypted integer. It is no longer needed. */ 2175 BN_clear_free(session_key_int); 2176 2177 /* Set the session key. From this on all communications will be encrypted. */ 2178 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2179 2180 /* Destroy our copy of the session key. It is no longer needed. */ 2181 memset(session_key, 0, sizeof(session_key)); 2182 2183 debug("Received session key; encryption turned on."); 2184 2185 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2186 packet_start(SSH_SMSG_SUCCESS); 2187 packet_send(); 2188 packet_write_wait(); 2189 } 2190 2191 /* 2192 * SSH2 key exchange: diffie-hellman-group1-sha1 2193 */ 2194 static void 2195 do_ssh2_kex(void) 2196 { 2197 Kex *kex; 2198 2199 if (options.ciphers != NULL) { 2200 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2201 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2202 } 2203 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2204 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2205 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2206 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2207 2208 if (options.macs != NULL) { 2209 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2210 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2211 } 2212 if (options.compression == COMP_NONE) { 2213 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2214 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2215 } else if (options.compression == COMP_DELAYED) { 2216 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2217 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2218 } 2219 2220 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); 2221 2222 /* start key exchange */ 2223 kex = kex_setup(myproposal); 2224 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2225 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2226 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2227 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2228 kex->server = 1; 2229 kex->client_version_string=client_version_string; 2230 kex->server_version_string=server_version_string; 2231 kex->load_host_key=&get_hostkey_by_type; 2232 kex->host_key_index=&get_hostkey_index; 2233 2234 xxx_kex = kex; 2235 2236 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2237 2238 session_id2 = kex->session_id; 2239 session_id2_len = kex->session_id_len; 2240 2241 #ifdef DEBUG_KEXDH 2242 /* send 1st encrypted/maced/compressed message */ 2243 packet_start(SSH2_MSG_IGNORE); 2244 packet_put_cstring("markus"); 2245 packet_send(); 2246 packet_write_wait(); 2247 #endif 2248 debug("KEX done"); 2249 } 2250 2251 /* server specific fatal cleanup */ 2252 void 2253 cleanup_exit(int i) 2254 { 2255 if (the_authctxt) 2256 do_cleanup(the_authctxt); 2257 #ifdef SSH_AUDIT_EVENTS 2258 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2259 if (!use_privsep || mm_is_monitor()) 2260 audit_event(SSH_CONNECTION_ABANDON); 2261 #endif 2262 _exit(i); 2263 } 2264